The present invention discloses a mouthwash, comprising by weight parts: Rheum rhabarbarum 20-30, bamboo leaf 20-30, Rhizoma phragmitis 6-8, green tea 20-40, Rhizoma anemarrhenae 20-40, and Wolfiporia extensa 20-40.The preparation method of the mouthwash comprises the following steps: mixing and grinding the raw materials to obtain a to-be-used paste adding 200-400 weight parts of pure water into the paste, and gently heating to decoct for 40-60 min and filtering, after decocting, to obtain a supernatant as the mouthwash finished product.
